Accurate full superfine group resonance self-shielding method with fission source and upscattering effects in thermal lattice

Abstract

This paper focused upon an approach to the promotion of the resonance self-shielding treatment to overwhelm the reaction rates deviation that mitigating frequent assumption of the ultrafine energy group method. Our first major finding is implementation of both the dependency of the fission source on incident neutron energy and thermal upscattering matrix at desired energy mesh on effective cross section. Moreover, the escape cross section correction (EC) method reflecting geometrical effect of 2D lattice is proposed to revise 1D cylindrical model on coarse group cross section collapsing by SPH method. After verifying the superfine library generation module, called UFEMR, various benchmark calculations for pin cell and fuel assembly are tested against the results of corresponding Monte Carlo solutions. The average relative error of the reaction rates by developed cross section generation module and use of the proposed superfine group structure is around 0.74%. The regionwise flux and reaction rates are in good agreement with Monte Carlo reference solutions.